1. Field of the Invention
The present invention relates to a driving support apparatus for a vehicle performing cruise control through throttle control and brake application control.
2. Description of Related Art
In related art, there have been various proposals for driving support apparatuses configured to recognize a vehicle exterior environment in front of a subject vehicle by using a millimeter wave radar, an infrared laser radar, a stereo camera, a monocular camera or the like, and perform cruise control or the like of the subject vehicle based on the recognized vehicle exterior environment. As an example of such cruise control functions, there is widely known a function of performing follow-up cruise control to follow a preceding vehicle when such a preceding vehicle is detected (captured) in front of a subject vehicle. Typically, the follow-up cruise control has been widely in practical use as part of adaptive cruise control (ACC). In the ACC, the follow-up cruise control is performed in a state where a vehicle is detected in front of a subject vehicle, while constant speed cruise control at a set vehicle speed set by a driver is performed in a state where no preceding vehicle is detected. Furthermore, in recent years, techniques of extending the range to which the follow-up cruise control is applied to a very low speed and stopping a subject vehicle while maintaining a constant inter-vehicle distance when a preceding vehicle has stopped (follow-up stop control) have been developed and in practical use.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2001-225669 discloses a technique of performing control of the opening degree of an electronic throttle and drive control of a brake actuator so as to keep the inter-vehicle time period at a target time period when the subject vehicle speed is higher than 20 km/h, and performing control of the opening degree of the electronic throttle and drive control of the brake actuator so as to accelerate or decelerate the subject vehicle in proportion to a deviation of an inter-vehicle distance to the front vehicle from a minimum inter-vehicle distance (=10 m) when the subject vehicle speed is 20 km/h or lower. In addition, JP-A No. 2001-225669 discloses a technique of decreasing the subject vehicle speed to a very low speed (5 km/h, for example) when stopping of a preceding vehicle is detected, and performing control of the opening degree of the electronic control throttle and drive control of the brake actuator so as to stop the subject vehicle at a point where the inter-vehicle distance becomes a stopping inter-vehicle distance (=5 m).
An example of a possible situation in which a preceding vehicle stops or decelerates is that a stop signal (a yellow light or a red light) is present ahead on a road on which the subject vehicle is traveling.
With the techniques disclosed in JP-A No. 2001-225669 described above, however, the subject vehicle is decelerated following the deceleration of the preceding vehicle. Therefore, the subject vehicle may not be decelerated promptly even though the driver has recognized a stop signal. Accordingly, it is desired to perform suitable cruise control against an extended range of objects to cover traffic signals on the road on which the subject vehicle is traveling in addition to the preceding vehicle so as to improve the convenience of the ACC.